I really hate to add weight to a plane to achieve ballance so that is always a last resort for me. First, only because this is the beginners forum, I will ask if the fuel tank is empty? C/G is checked with the fuel tank empty. Also, what engine did you put on the nose that could be weighing it down so much? You probably would not be the first to put a 2 stroke .90 on a .60 size plane but that would obviously cause C/G issues in which case 4 oz. of lead would not be unreasonable. Also put the aircraft on your C/G machine at the point it does ballance and mark it and measure it and let us know how far off it is from the manuals specification. The C/G location is measured from the leading edge of the wing towards the back. This ballance point should be about 25%-30% of the wings chord (the measurement from the wings leading edge to it's trailing edge aka: front to back). for example if your wing measures a 14 inch wing chord 25% of that would be 3.5 inches from the leading edge and 30% would be 4.2 inches. Also if you can upload a picture of the plane ballanced on the C/G machine maybe we can see in it if there is anything you might be doing wrong and help you correct it. Good luck and congrats on the new plane.